A common type of metallic-convenience closure comprises a panel with an endless score line forming a central removable portion and a peripheral fixed portion that is attached to the cylindrical container. A pull-tab having a nose portion is fastened to the removable portion by a rivet so that when the pull-tab is manually grasped, the nose portion of the pull-tab moves into position adjacent the score line severing the panel. Further movement of the pull-tab completes the severing to remove the removable portion. Typical patents showing such construction are U.S. Pat. Nos. 3,696,961, 3,705,563, 3,819,083 and 3,986,632.
One of the problems with respect to convenience closures is that there is a tendency for the pull-tab to rotate about the rivet axis either during handling of the container or during opening. If the pull-tab rotates more than a predetermined amount, then it is difficult if not impossible to open the convenience closure since the nose portion of the tab will not be close enough to the score line to cause a severing thereof.
Accordingly, among the objectives of the present invention are to provide a metallic convenience closure which will prevent rotation of the pull-tab and thereby insure registration of the nose portion of the pull-tab with the score line. Among the objectives of the present invention are to provide a novel method and apparatus for making the metallic-convenience closure.
In accordance with the invention, a portion of the removable portion of the panel of the closure is deformed adjacent a portion of the tab that is riveted to the removable portion to prevent rotation of the tab and maintain registry of the nose portion of the tab with the score line. After the pull-tab is attached to the closure with the second portion of the pull-tab extending radially outwardly toward the score line of the panel, opposed clamping forces are applied to the exposed surface of the manual graspable portion, and the portion of the pull-tab attached to the removable portion of the panel, and a force is applied to the portion of the panel surrounded by the graspable portion of the pull-tab to deform the portion upwardly into the area surrounded by the graspable portion so that the deformed portion prevents rotation about the axis of the rivet.